1. Field of the Invention
The invention relates in general to a controller for an audio device and an associated operation method, and more particularly to an audio device controller that effectively improves a sound collecting effect with a low computation amount, and an associated operation method.
2. Description of the Related Art
Audio devices that can collect and/or play sounds play an essential role in the modern information society. Devices that support voice control are also regarded as audio devices. For example, audio devices cover cell phones, digital cameras/video cameras, navigation/positioning systems, wearable/handheld/portable calculators/electronic books/electronic dictionaries/computers that produce sounds and receive voice control, televisions, sound systems, multimedia players, toys with voice control, and interactive artworks.
FIG. 1 shows a schematic diagram of a conventional audio device 10, which is capable of playing sounds and receiving voice control. The audio device 10 includes microphones 12a and 12b, speakers 14a and 14b, a controller 20, an audio output module 23, and a playback module 24. The microphones 12a and 12b collect sounds, and convert the collected sounds to signals Si_L and Si_R. The signals Si_L and Si_R are transmitted to the controller 20.
The controller 20 includes a beamforming module 16, an echo cancellation module 18, and a speech recognition module 22. The audio output module 23 provides signals Sp_L and Sp_R as audio source signals. The playback module 24 performs playback according to the signals Sp_L and Sp_R. For example, the playback module 24 drives the speakers 14a and 14b according to the signals Sp_L and Sp_R, respectively, to play the signals Sp_L and Sp_R as sounds.
To realize the voice control function, the audio device 10 needs to focus at a position of a user to centrally collect a voice control command issued by the user. Since sounds played by the speakers 14a and 14b form an echo that can be received by the microphones 12a and 12b, the audio device 10 also needs to prevent the speakers 14a and 14b from affecting the sound collection. In the controller 20 of the conventional audio device 10, the beamforming module 16 primarily utilizes the signals Si_L and Si_R for beamforming to accordingly provide a signal Sm1. One object of the beamforming is to enhance the sound within a certain focal area in the signal Sm1 while suppressing sound interferences of other non-focal areas. The echo cancellation module 18 performs echo cancellation on the signal Sm1 according to the signal Sp_R to accordingly provide a signal Sm2. The speech recognition module 22 then utilizes the signal Sm2 for speech recognition, and identifies whether the signal Sm2 contains a voice control command and associated contents of the command. Thus, the controller 20 is enabled to accordingly control the audio device 10.
Known from FIG. 1, the conventional audio device 10 performs echo cancellation after having performed beamforming. Under such conventional architecture, although the controller 20 requires only one single echo cancellation module 18 and thus has a reduced computation amount, the beamforming may nevertheless destruct the linearity of the echo and generate non-linear signals. As a result, the echo cancellation module 18 may fail to completely eliminate the echo to undesirably affect the accuracy and recognition rate of speech recognition.